Image sensor including color separation element and image pickup apparatus including the image sensor

ABSTRACT

An image sensor includes a pixel array having a Bayer pattern structure including a first pixel row in which first pixels and second pixels are alternately provided and a second pixel row in which additional ones of the second pixels and third pixels are alternately provided, a first element to control light of a first wavelength band to travel in directions toward left and right sides of the first element and to control light of a second wavelength band of the incident light to travel in a direction directly under the first element, and a second element to control light of a third wavelength band to travel in the directions toward the left and right sides of the second element and to control the light of the second wavelength band to travel in a direction directly under the second element.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.14/791,746, filed Jul. 6, 2015, which claims the benefit of KoreanPatent Application No. 10-2014-0083233, filed on Jul. 3, 2014, in theKorean Intellectual Property Office, the disclosures of which areincorporated herein by reference in their entireties.

BACKGROUND 1. Field

The exemplary embodiments relate to an image sensor including a colorseparation element and an image pickup apparatus including the imagesensor, and more particularly, to an image sensor having an improvedlight use efficiency by using a color separation element, and an imagepickup apparatus including the image sensor.

2. Description of the Related Art

Color display devices or color image sensors usually display an image ofvarious colors or detect a color of incident light by using a colorfilter. An RGB color filter method, in which, for example, a greenfilter is arranged at two pixels of four pixels and a blue filter and ared filter are arranged in the other two pixels, is most widely employedby a currently used color display device or color image sensor. Inaddition to the RGB color filter method, a CYGM color filter method maybe employed in which color filters of cyan, yellow, green, and magenta,which are complementary colors, are respectively arranged at fourpixels.

However, a color filter may have a low light use efficiency because thecolor filter absorbs light of colors other than a color corresponding tothe color filter. For example, when an RGB color filter is in use, only⅓ of the incident light is transmitted and the other portion, that is,⅔, of the incident light is absorbed. Accordingly, the light useefficiency may be about 33%. Accordingly, for the color display deviceor a color image sensor, most of a light loss is generated in the colorfilter.

Recently, to improve the light use efficiency of the color displaydevice or color image sensor, a color separation element is being usedinstead of the color filter. The color separation element may separatethe color of an incident light by using the diffraction or refractioncharacteristics of light that vary according to a wavelength of thelight. The colors separated by the color separation element may beprovided to pixels corresponding to the colors, respectively.

SUMMARY

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the presented exemplary embodiments.

According to an aspect of an exemplary embodiment, there is provided animage sensor including a pixel array including Bayer patterns, each ofthe Bayer patterns including a first pixel and a third pixel provided ina first diagonal direction and two second pixels provided in a seconddiagonal direction crossing the first diagonal direction, and a colorseparation element provided to face the second pixels in the seconddiagonal direction, wherein the color separation element is configuredto control light of a first wavelength band of incident light to travelin a first lateral direction of the color separation element toward thefirst pixel, to control light of a third wavelength band of the incidentlight to travel in a second lateral direction of the color separationelement toward the third pixel, and to control light of a secondwavelength band of the incident light to travel in a downward directionof the color separation element toward the second pixels.

The image sensor may further include a color filter layer that isprovided on the pixel array, wherein the color filter layer includes atleast one of a first color filter provided adjacent to the first pixel,a second color filter provided adjacent to the second pixel, and a thirdcolor filter provided adjacent to the third pixel.

The image sensor may further include a transparent dielectric layerprovided on the color filter layer, and a microlens provided on thetransparent dielectric layer.

The microlens may be provided to face the pixel array including theBayer patterns.

According to another aspect of an exemplary embodiment, there isprovided an image sensor including a pixel array including Bayerpatterns, each of the Bayer patterns including a first pixel and a thirdpixel provided in a first diagonal direction and two second pixelsprovided in a second diagonal direction crossing the first diagonaldirection, color separation elements provided to face the second pixels,respectively, and a color filter layer provided on the pixel array,wherein each of the color separation elements is configured to controllight of a second wavelength band of incident light to travel in adownward direction of the color separation element and to control mixedlight including a mixture of light of a first wavelength band of theincident light and light of a third wavelength band of the incidentlight to travel in directions toward left and right sides of the colorseparation element.

One of the color separation elements may include a first colorseparation element provided in a first direction and a second colorseparation element provided in a second direction perpendicular to thefirst direction.

The first color separation element and the second color element may bealternately provided to face the second pixels.

Both of the first color separation element and the second color elementmay be provided adjacent to one of the second pixels.

The color separation elements may be oriented in the second diagonaldirection.

One of the color separation elements may include a first colorseparation element oriented in the first diagonal direction and a secondcolor separation element oriented in the second diagonal direction.

The image sensor may further include a transparent dielectric layerprovided on the color filter layer, and microlenses provided on thetransparent dielectric layer, wherein the microlenses are separatelyprovided at each of the first, second, and third pixels.

The light of the second wavelength band separated by the colorseparation elements may be incident on the second pixels and the mixedlight of the first and second wavelength bands and a white light may beincident together on the first and third pixels.

The color filter layer may include a first color filter provided on thefirst pixel and configured to transmit the light of the first wavelengthband and a third color filter provided on the third pixel and configuredto transmit the light of the third wavelength band.

The light of the first wavelength band may be red light, the light ofthe second wavelength band may be green light, and the light of thethird wavelength band may be blue light.

According to another aspect of an exemplary embodiment, there isprovided an image sensor including a pixel array including a first pixeland a third pixel provided in a first diagonal direction and two secondpixels provided in a second diagonal direction crossing the firstdiagonal direction, and a first color separation element oriented in thesecond diagonal direction and facing the second pixels.

The image sensor may further include a second color separation elementoriented in the first diagonal direction and facing the second pixels.

The first color separation element may be configured to control light ofa first wavelength band of incident light to travel in a first lateraldirection of the first color separation element toward the first pixel,to control light of a third wavelength band of the incident light totravel in a second lateral direction of the first color separationelement toward the third pixel, and to control light of a secondwavelength band of the incident light to travel in a downward directionof the first color separation element toward the second pixels.

The second color separation element may be configured to control lightof a first wavelength band of incident light to travel in a firstlateral direction of the second color separation element toward thefirst pixel, to control light of a third wavelength band of the incidentlight to travel in a second lateral direction of the second colorseparation element toward the third pixel, and to control light of asecond wavelength band of the incident light to travel in a downwarddirection of the second color separation element toward the secondpixels.

The image sensor may further include a color filter layer that isprovided on the pixel array, wherein the color filter layer may includeat least one of a first color filter provided adjacent to the firstpixel, a second color filter provided adjacent to one of the secondpixels, and a third color filter provided adjacent to the third pixel.

The image sensor may further include a transparent dielectric layerprovided on the color filter layer, wherein the first color separationelement may be buried in the transparent dielectric layer.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects will become apparent and more readilyappreciated from the following description of the exemplary embodiments,taken in conjunction with the accompanying drawings in which:

FIGS. 1, 2, 3 and 4 are cross-sectional views schematically andexemplarily illustrating the color separation characteristics of variouscolor separation elements;

FIG. 5 is a plan view schematically illustrating a pixel structure of animage sensor including the color separation elements of FIGS. 1 and 2,according to an exemplary embodiment;

FIG. 6A is a cross-sectional view taken along the line A-A′ of the imagesensor of FIG. 5;

FIG. 6B is a cross-sectional view taken along the line B-B′ of the imagesensor of FIG. 5;

FIG. 7 is a plan view schematically illustrating a pixel structure of animage sensor including the color separation element of FIG. 3, accordingto another exemplary embodiment;

FIG. 8 is a plan view schematically illustrating a pixel structure of animage sensor including the color separation element of FIG. 4, accordingto another exemplary embodiment;

FIG. 9A is a cross-sectional view taken along the line C-C′ of the imagesensor of FIG. 8;

FIG. 9B is a cross-sectional view taken along the line D-D′ of the imagesensor of FIG. 8;

FIG. 10 is a graph exemplarily showing spectrum distributions of lightincident on the pixels of the image sensor of FIG. 8;

FIG. 11 is a graph exemplarily showing spectrum distributions of lightabsorbed by the pixels of the image sensor of FIG. 8; and

FIGS. 12, 13, 14 and 15 are plan views schematically illustrating pixelstructures of image sensors according to various other exemplaryembodiments.

DETAILED DESCRIPTION

Reference will now be made in detail to exemplary embodiments, examplesof which are illustrated in the accompanying drawings, wherein likereference numerals refer to like elements throughout. In this regard,the present exemplary embodiments may have different forms and shouldnot be construed as being limited to the descriptions set forth herein.Accordingly, the exemplary embodiments are merely described below, byreferring to the figures, to explain aspects of the exemplaryembodiments. Expressions such as “at least one of,” when preceding alist of elements, modify the entire list of elements and do not modifythe individual elements of the list.

An image sensor including a color separation element, and an imagepickup apparatus including the image sensor, are described in detailwith reference to the accompanying drawings. In the followingdescriptions, like reference numerals refer to like elements. In thedrawings, the size of each element is exaggerated for clarity andconvenience of explanation. Also, in the following description of alayer structure, when a layer is described to exist “on” or “above”another layer, the layer may exist directly on or indirectly above theother layer, or a third layer may be interposed therebetween.

FIGS. 1, 2, 3 and 4 are cross-sectional views schematically andexemplarily illustrating the color separation characteristics of variouscolor separation elements 131, 132, 133, and 134. The color separationelements 131, 132, 133, and 134 separate incident light according to awavelength thereof to allow light of different wavelength bands totravel along different paths. The color separation elements 131, 132,133, and 134 change the traveling paths of light according to thewavelengths of incident lights by using diffraction or refractioncharacteristics of light varying according to the wavelength thereof.For example, the color separation elements 131, 132, 133, and 134 have avariety of shapes such as a rod shape having a transparent symmetricalor asymmetrical structure or a prism shape having an inclined surface,and various designs for a color separation element according to adesired spectrum distribution of an exit light may be available.

For example, referring to FIG. 1, the first color separation element 131may be configured to allow (e.g., control) light C1 of a firstwavelength band of an incident light to travel in oblique directionstoward the left and right sides and light C2 of a second wavelength bandof the incident light to travel in a direction along a center axis, thatis, in a direction directly under the first color separation element131. Also, referring to FIG. 2, the second color separation element 132may be configured to allow light C3 of a third wavelength band of theincident light to travel in oblique directions toward the left and rightsides and the light C2 of the second wavelength band of the incidentlight to travel in the direction along the center axis. Also, referringto FIG. 3, the third color separation element 133 may be configured toallow the light C1 of the first wavelength band of the incident light totravel in an oblique direction toward the left side, the light C2 of thesecond wavelength band of the incident light to travel in the directionalong the center axis, and the light C3 of the third wavelength band ofthe incident light to travel in the oblique direction toward the rightside. Referring to FIG. 4, the fourth color separation element 134 maybe configured to allow the light C2 of the second wavelength band of theincident light to travel in the direction along the center axis andlight C1+C3 of the other wavelength band of the incident light to travelin oblique directions toward the left and right sides. In other words,the light separated by the fourth color separation element 134 andtraveling in the direction toward the left and right sides may be amixed light of the light C1 of the first wavelength band and the lightC3 of the third wavelength band. For example, the light C1 of the firstwavelength band may be a red-based light, the light C2 of the secondwavelength band may be a green-based light, and the light C3 of thethird wavelength band may be blue-based light. However, the presentexemplary embodiment is not limited thereto.

The first to fourth color separation elements 131, 132, 133, and 134each may be buried in a transparent dielectric layer 120 and fixedtherein as illustrated in FIGS. 1 to 4. A microlens 140 may be arrangedon each of the first to fourth color separation elements 131, 132, 133,and 134 to focus the incident light onto each of the first to fourthcolor separation elements 131, 132, 133, and 134. However, thearrangement of the microlens 140 is optional and may be omitted if thecolor separation efficiency of each of the first to fourth colorseparation elements 131, 132, 133, and 134 is sufficiently high.

In order to sufficiently diffract and refract the incident light, thefirst to fourth color separation elements 131, 132, 133, and 134 may beformed of a material having a refractive index higher than that ofsurroundings. In other words, the refractive indexes of the first tofourth color separation elements 131, 132, 133, and 134 may be higherthan that of the transparent dielectric layer 120. For example, thetransparent dielectric layer 120 may be formed of SiO₂ or siloxane-basedspin on glass (SOG). The first to fourth color separation elements 131,132, 133, and 134 may be formed of a high refractive material such asTiO₂, SiN₃, ZnS, ZnSe, and Si₃N₄. The detailed shapes and materials ofthe first to fourth color separation elements 131, 132, 133, and 134 maybe diversely selected according to desired color separationcharacteristics.

FIG. 5 is a plan view schematically illustrating a pixel structure of animage sensor including the first and second color separation elements131 and 132 of FIGS. 1 and 2, according to an exemplary embodiment.Referring to FIG. 5, the image sensor may have a Bayer pattern structurein which a first pixel 110 a and a third pixel 110 c are arranged in afirst diagonal direction and two second pixels 110 b are arranged in asecond diagonal direction crossing the first diagonal direction.Although FIG. 5 illustrates one unit having a Bayer pattern, the imagesensor may include a pixel array including a plurality of Bayer patternsarranged in two dimensions. For example, the image sensor may include afirst pixel row P1 in which a plurality of second pixels 110 b and aplurality of third pixels 110 c are alternately arranged in a horizontaldirection and a plurality of first pixels 110 a and a plurality ofsecond pixels 110 b are alternately arranged in the horizontaldirection. A plurality of first pixel rows P1 and a plurality of secondpixel rows P2 may be alternately arranged in a vertical direction.

Also, the image sensor may include the second color separation element132 that is arranged facing the second pixel 110 b in the first pixelrow P1 and the first color separation element 131 that is arrangedfacing the second pixel 110 b in the second pixel row P2. As describedabove, the first color separation element 131 may allow the light C1 ofthe first wavelength band of the incident light to obliquely traveltoward the left and right sides and the light C2 of the secondwavelength band of the incident light to travel in the directiondirectly under the first color separation element 131. Accordingly, thelight C1 of the first wavelength band separated by the first colorseparation element 131 may be incident on the first pixel 110 a adjacentto the second pixel 110 b in the second pixel row P2 and the light C2 ofthe second wavelength band may be incident on the second pixel 110 bfacing the first color separation element 131 in the second pixel rowP2. Also, the second color separation element 132 may allow the light C3of the third wavelength band of the incident light to obliquely traveltoward the left and right sides and the light C2 of the secondwavelength band to travel in the direction directly under the secondcolor separation element 132. Accordingly, the light C3 of the thirdwavelength band separated by the second color separation element 132 maybe incident on the third pixel 110 c adjacent to the second pixel 110 bin the first pixel row P1 and the light C2 of the second wavelength bandmay be incident on the second pixel 110 b facing the second colorseparation element 132 in the first pixel row P1.

FIG. 6A is a cross-sectional view taken along the line A-A′ of the firstpixel row P1 of the image sensor of FIG. 5. Referring to FIG. 6A, thefirst pixel row P1 of the image sensor may include a light sensing layer110 that converts the intensity of incident light to an electric signal,a color filter layer 150 arranged on the light sensing layer 110 andthat transmits light of a desired wavelength band only, the transparentdielectric layer 120 arranged on the color filter layer 150, the secondcolor separation element 132 buried in the transparent dielectric layer120 and fixed therein, and the microlens 140 arranged on the transparentdielectric layer 120. The second pixel 110 b and the third pixel 110 cmay be arranged in the light sensing layer 110 in the first pixel rowP1. The color filter layer 150 may include a second color filter CF2that is arranged on the second pixel 110 b and that transmits only thelight C2 of the second wavelength band and a third color filter CF3 thatis arranged on the third pixel 110 c and that transmits only the lightC3 of the third wavelength band. The second color separation element 132may be arranged facing the second pixel 110 b.

As illustrated in FIG. 6A, of the light incident on the second colorseparation element 132, the light C2 of the second wavelength band maybe incident on the second pixel 110 b by passing through the secondcolor filter CF2 disposed directly under the second color separationelement 132. Also, the light C3 of the third wavelength band may beincident on the third pixel 110 c by obliquely traveling toward the leftand right sides of the second color separation element 132 and passingthrough the third color filter CF3. Even when the second and third colorfilters CF2 and CF3 are used, the light C2 and C3 that arecolor-separated to a considerable degree by the second color separationelement 132 are incident on the second and third color filters CF2 andCF3, respectively, and thus loss of light due to the color filter layer150 is not severe. If the color separation by the second colorseparation element 132 is sufficient, the color filter layer 150 may beomitted. Alternatively, some of the second and third color filters CF2and CF3 may be omitted.

FIG. 6B is a cross-sectional view taken along the line B-B′ of thesecond pixel row P2 of the image sensor of FIG. 5. Referring to FIG. 6B,the second pixel row P2 of the image sensor may include the lightsensing layer 110 that converts the intensity of incident light to anelectric signal, the color filter layer 150 arranged on the lightsensing layer 110 and that transmits light of a desired wavelength bandonly, the transparent dielectric layer 120 arranged on the color filterlayer 150, the first color separation element 131 buried in thetransparent dielectric layer 120 and fixed therein, and the microlens140 arranged on the transparent dielectric layer 120. The first pixel110 a and the second pixel 110 b may be arranged in the light sensinglayer 110 in the second pixel row P2. The color filter layer 150 mayinclude the first color filter CF1 that is arranged on the first pixel110 a and that transmits only the light C1 of the first wavelength bandand the second color filter CF2 that is arranged on the second pixel 110b and that transmits only the light C2 of the second wavelength band.The first color separation element 131 may be arranged facing the secondpixel 110 b. Alternatively, some of the first and second color filtersCF1 and CF2 may be omitted.

As illustrated in FIG. 6B, of the light incident on the first colorseparation element 131, the light C2 of the second wavelength band maybe incident on the second pixel 110 b by passing through the secondcolor filter CF2 disposed directly under the first color separationelement 131. Also, the light C1 of the first wavelength band may beincident on the first pixel 110 a by obliquely traveling toward the leftand right sides of the first color separation element 131 and passingthrough the first color filter CF1. In the second pixel row P2, if thecolor separation by the first color separation element 131 issufficient, the color filter layer 150 may be omitted.

As illustrated in FIGS. 6A and 6B, in the first pixel row P1, themicrolens 140 may be arranged extending in the third pixel 110 cdisposed at the opposite sides of the second pixel 110 b. Also, in thesecond pixel row P2, the microlens 140 may be arranged extending in thefirst pixel 110 a disposed at the opposite sides of the second pixel 110b. However, the image sensor according to the present exemplaryembodiment may not include only the microlens 140 illustrated in FIGS.6A and 6B. For example, a microlens 142 (refer to FIG. 9A) separatelyprovided for each of the pixels 110 a, 110 b, and 110 c may be used, orthe microlens 140 may be omitted.

In the image sensor according to the present exemplary embodiment,improved light use efficiency and superior color purity may besimultaneously achieved by using the first and second color separationelements 131 and 132. Furthermore, since the Bayer pattern that isgenerally adopted in the image sensor is used without a change, thepixel structure and image processing algorithm of an image sensor of therelated art do not need to be substantially changed. The image sensoraccording to the present exemplary embodiment may provide an image ofsuperior quality by being applied to a variety of types of image pickupapparatuses.

FIG. 7 is a plan view schematically illustrating a pixel structure of animage sensor including the third color separation element 133 of FIG. 3,according to another exemplary embodiment. Referring to FIG. 7, theimage sensor may include a pixel array of a Bayer pattern structure thatis the same as that of FIG. 5. In other words, the image sensorillustrated in FIG. 7 may include a Bayer pattern having the first pixel110 a and the third pixel 110 c arranged in a first diagonal directionand two second pixels 110 b arranged in a second diagonal directioncrossing the first diagonal direction.

Also, the image sensor according to the present exemplary embodiment mayinclude the third color separation element 133 that is arranged in thesecond diagonal direction. As illustrated in FIG. 7, the third colorseparation element 133 may be arranged in the second diagonal directionfacing the two second pixels 110 b. As described above, the third colorseparation element 133 may allow the light C1 of the first wavelengthband of incident light to obliquely travel in a direction toward theleft side, the light C2 of the second wavelength band of the incidentlight to travel in a direction directly under the third color separationelement 133, and the light C3 of the third wavelength band of incidentlight to obliquely travel in a direction toward the right side.Accordingly, the light C1 of the first wavelength band separated by thethird color separation element 133 may be incident on the first pixel110 a disposed at the left side of the third color separation element133, and the light C2 of the second wavelength band separated by thethird color separation element 133 may be incident on the two secondpixels 110 b disposed directly under the third color separation element133. Also, the light C3 of the third wavelength band separated by thethird color separation element 133 may be incident on the third pixel110 c disposed at the right side of the third color separation element133. In order to prevent mixture of colors, the first to third colorfilters CF1, CF2, and CF3 illustrated in FIGS. 6A and 6B may be furtherrespectively arranged at the first to third pixels 110 a, 110 b, and 110c corresponding thereto.

Also, the image sensor according to the present exemplary embodiment mayfurther include a microlens 141 facing one unit having a Bayer patternas indicated by a dotted line in FIG. 7. In this case, the microlens 141may face the first pixel 110 a and the third pixel 110 c arranged in thefirst diagonal direction and the two second pixels 110 b arranged in thesecond diagonal direction. However, the image sensor may not includeonly the microlens 141 of FIG. 7. For example, a microlens 143 (refer toFIG. 14) that is arranged in the second diagonal direction along thethird color separation element 133 or the microlens 142 of FIG. 9Aseparately arranged for each of the pixels 110 a, 110 b, and 110 c maybe used, or the microlens 140 may be omitted.

FIG. 8 is a plan view schematically illustrating a pixel structure of animage sensor including the color separation element 134 of FIG. 4,according to another exemplary embodiment. Referring to FIG. 8, theimage sensor may include a pixel array having a Bayer pattern structurethat is the same as that of FIG. 5. In other words, the image sensorillustrated in FIG. 8 may include a Bayer pattern having the first pixel110 a and the third pixel 110 c arranged in the first diagonal directionand the two second pixels 110 b arranged in the second diagonaldirection.

Also, the image sensor according to the present exemplary embodiment mayfurther include the fourth color separation element 134 that is arrangedfacing the second pixel 110 b. In other words, the fourth colorseparation element 134 may be arranged facing the second pixel 110 b inthe first pixel row P1 and the second pixel 110 b in the second pixelrow P2. As described above, the fourth color separation element 134 mayallow the light C2 of the second wavelength band of the incident lightto travel in a direction directly under the fourth color separationelement 134 and the light C1+C3 of the other wavelength band of theincident light to travel in oblique directions toward the left and rightsides. Accordingly, the light C2 of the second wavelength band separatedby the fourth color separation element 134 may be incident on the secondpixel 110 b of each of the first and second pixel rows P1 and P2. Also,the light C1+C3 of the other wavelength band, that is, a mixed light ofthe first light C1 of the first wavelength band and the third light C3of the third wavelength band, may be incident on each of the third pixel110 c adjacent to the second pixel 110 b in the first pixel row P1 andthe first pixel 110 a adjacent to the second pixel 110 b in the secondpixel row P2. For example, when the first light C1 of the firstwavelength band is based on red, the second light C2 of the secondwavelength band is based on green, and the third light C3 of the thirdwavelength band is based on blue, a green light may be incident on thesecond pixel 110 b and magenta light may be incident on the first andthird pixels 110 a and 110 c.

FIG. 9A is a cross-sectional view taken along the line C-C′ of the firstpixel row P1 in the image sensor of FIG. 8. FIG. 9B is a cross-sectionalview taken along the line D-D′ of the second pixel row P2 in the imagesensor of FIG. 8. Referring to FIGS. 9A and 9B, the image sensoraccording to the present exemplary embodiment may further include thelight sensing layer 110 that converts the intensity of incident light toan electric signal, the color filter layer 150 arranged on the lightsensing layer 110, the transparent dielectric layer 120 arranged on thecolor filter layer 150, the fourth color separation element 134 buriedin the transparent dielectric layer 120 and fixed therein, and themicrolens 142 arranged on the transparent dielectric layer 120.

The second pixel 110 b and the third pixel 110 c may be arranged in thelight sensing layer 110 of the first pixel row P1. The first pixel 110 aand the second pixel 110 b may be arranged in the light sensing layer110 of the second pixel row P2. Also, in the first pixel row P1, thecolor filter layer 150 may include only the third color filter CF3 thatis arranged on the third pixel 110 c and, in the second pixel row P2,the color filter layer 150 may include only the first color filter CF1that is arranged on the first pixel 110 a. Accordingly, with respect tothe light C1+C3 that is a mixed light of the first light C1 of the firstwavelength band and the third light C3 of the third wavelength band, thethird pixel 110 c may absorb only the light C3 of the third wavelengthband and the first pixel 110 a may absorb only the light C1 of the firstwavelength band. If the color separation efficiency is sufficientlyhigh, a color filter may not be arranged on the second pixel 110 b.However, to increase color purity, the second color filter CF2 may bearranged on the second pixel 110 b. The fourth color separation element134 may be arranged facing the second pixel 110 b in the first pixel rowP1 and the second pixel row P2.

Also, the microlens 142 may be separately arranged at each of the pixels110 a, 110 b, and 110 c. For example, the microlens 142 having one pixelsize may be arranged at each of the first pixel 110 a, the second pixel110 b, and the third pixel 110 c. Then, only the light C2 of the secondwavelength band of the light incident on the microlens 142 disposed onthe second pixel 110 b may be separated by the fourth color separationelement 134 and provided to the second pixel 110 b. The light C1+C3 ofthe first and third wavelength bands of the light incident on themicrolens 142 disposed on the second pixel 110 b may be separated by thefourth color separation element 134 and provided to the first pixel 110a adjacent to the opposite sides of the second pixel 110 b (in case ofthe second pixel row P2) or the third pixel 110 c (in case of the firstpixel row P1). The light incident on the microlens 142 disposed on thefirst pixel 110 a or the third pixel 110 c is incident on the firstpixel 110 a or the third pixel 110 c corresponding to the microlens 142without a change. Accordingly, the light incident on the first and thirdpixels 110 a and 110 c is a sum of the light C1+C3 of the first andthird wavelength bands separated by the fourth color separation element134 and a white light passing through the microlens 142 corresponding tothe first and third pixels 110 a and 110 c.

For example, FIG. 10 is a graph exemplarily showing spectrumdistributions of light incident on the pixels 110 a, 110 b, and 110 c ofthe image sensor of FIG. 8, when the light C1 of the first wavelengthband is a red light, the light C2 of the second wavelength band is agreen light, and the light C3 of the third wavelength band is a bluelight. In FIG. 10, a graph indicated by a dotted line indicates aspectrum distribution of light incident on the second pixel 110 b, whichshows that a green light component is the largest component. Also, inFIG. 10, a graph indicated by a solid line indicates a spectrumdistribution of light incident on the first and third pixels 110 a and110 c, which shows that a red light component and a blue light componentare larger than a green light component. In particular, since the whitelight is further incident on the first and third pixels 110 a and 110 c,in FIG. 10, the graph indicated by a solid line is biased as large as alight amount of the white light, compared to the graph indicated by adotted line.

As described above, since the light incident on each of the first tothird pixels 110 a, 110 b, and 110 c not only has a particular spectrumdistribution but also has a large light amount, a high light useefficiency may be obtained even when the color filters CF1, CF2, and CF3are arranged at the respective pixels 110 a, 110 b, and 110 c. Forexample, FIG. 11 is a graph exemplarily showing spectrum distributionsof light absorbed by the first to third pixels 110 a, 110 b, and 110 cof the image sensor of FIG. 8 In the graph of FIG. 11, “R filter”denotes transmission characteristics of the first color filter CF1, “Gfilter” denotes transmission characteristics of the second color filterCF2, and “B filter” denotes transmission characteristics of the thirdcolor filter CF3. Also, in the graph of FIG. 11, “R” denotes anabsorption spectrum of the first pixel 110 a, “Gr” denotes an absorptionspectrum of the second pixel 110 b adjacent to the first pixel 110 a,that is, the second pixel 110 b arranged in the second pixel row P2,“Gb” denotes an absorption spectrum of the second pixel 110 b adjacentto the third pixel 110 c, that is, the second pixel 110 b arranged inthe first pixel row P1, and “B” denotes an absorption spectrum of thethird pixel 110 c. As illustrated in FIG. 11, a high light absorptionamount may be obtained at all of the first to third pixels 110 a, 110 b,and 110 c. Accordingly, an increase in the amplitude of a signal in theimage sensor may be expected.

FIGS. 12 to 15 are plan views schematically illustrating pixelstructures of image sensors according to various other exemplaryembodiments.

First, referring to FIG. 12, an image sensor according to the presentexemplary embodiment may include the fourth color separation elements134 and a plurality of fifth color separation elements 135 which arealternately arranged at the second pixels 110 b. For example, the fourthcolor separation element 134 may be arranged at the second pixel 110 bthat is the first one from the left side in the first pixel row P1, andthe fifth color separation element 135 may be arranged at the secondpixel 110 b that is the second one from the left side in the first pixelrow P1. The fifth color separation element 135 may be arranged at thesecond pixel 110 b that is the first one from the left side in thesecond pixel row P2, and the fourth color separation element 134 may bearranged at the second pixel 110 b that is the second one from the leftside in the second pixel row P2. The other structure of the image sensorof FIG. 12 may be the same as that of the image sensor of FIG. 8.

The fifth color separation element 135 has the same color separationcharacteristics as those of the fourth color separation element 134 andis rotated by 90° with respect to the fourth color separation element134. For example, the fourth color separation element 134 may allow thelight C2 of the second wavelength band to travel in a direction directlyunder the fourth color separation element 134 and the light C1+C3 of theother wavelength band to travel in a first lateral direction, forexample, in a horizontal direction in FIG. 12. In contrast, the fifthcolor separation element 135 may allow the light C2 of the secondwavelength band to travel in a direction directly under the fifth colorseparation element 135 and the light C1+C3 of the other wavelength bandto travel in a second lateral direction perpendicular to the firstlateral direction, for example, in a vertical direction in FIG. 12.

In the image sensor of FIG. 8, the first pixel 110 a and the third pixel110 c receive the light C1+C3 of the first and third wavelength bandsfrom the opposite side surfaces facing each other. However, for theimage sensor of FIG. 12, as indicated by arrows, the first pixel 110 aand the third pixel 110 c may receive the light C1+C3 of the first andthird wavelength bands from the two side surfaces vertically adjoiningeach other.

Also, referring to FIG. 13, an image sensor according to the presentexemplary embodiment may include a plurality of sixth color separationelements 136 arranged at the second pixels 110 b. The sixth colorseparation element 136 may be configured to allow the light C2 of thesecond wavelength band to travel in a direction directly under the sixthcolor separation element 136 and the light C1+C3 of the other wavelengthband to travel in four different directions perpendicular to oneanother. For example, the sixth color separation element 136 may beformed by combining the fourth color separation element 134 and thefifth color separation element 135. In other words, the sixth colorseparation element 136 may be formed by simultaneously arranging thefourth color separation element 134 and the fifth color separationelement 135 at one second pixel 110 b. For the image sensor of FIG. 13,as indicated by an arrow, the first pixel 110 a and the third pixel 110c may receive the light C1+C3 of the first and third wavelength bandsfrom all four side surfaces. The other structure of the image sensor ofFIG. 13 may be the same as that of the image sensor of FIG. 8.

Also, referring to FIG. 14, an image sensor according to the presentexemplary embodiment may include a seventh color separation element 137arranged in a diagonal direction. For example, assuming that the firstpixel 110 a and the third pixel 110 c are arranged in a first diagonaldirection and the second pixels 110 b are arranged in a second diagonaldirection crossing the first diagonal direction, the seventh colorseparation element 137 may be arranged facing the second pixels 110 b inthe second diagonal direction. The seventh color separation element 137may correspond to the fourth color separation element 134 that isoriented in the second diagonal direction. Accordingly, the seventhcolor separation element 137 may be configured to allow the light c2 ofthe second wavelength band to travel in a direction directly under theseventh color separation element 137 and the light C1+C3 of the otherwavelength band to travel in the first diagonal direction.

Also, as indicated by a dotted line, the image sensor may furtherinclude a plurality of microlenses 143 arranged in the second diagonaldirection along the seventh color separation element 137. For the imagesensor of FIG. 14, as indicated by an arrow, the first pixel 110 a andthe third pixel 110 c may receive the light C1+C3 of the first and thirdwavelength bands from the first diagonal direction.

Referring to FIG. 15, an image sensor according to the present exemplaryembodiment may include the seventh color separation element 137 arrangedfacing the second pixels 110 b in the second diagonal direction and aneighth color separation element 138 arranged facing the second pixels110 b in the first diagonal direction. The seventh color separationelement 137 may be configured to allow the light C2 of the secondwavelength band to travel in a direction directly under the seventhcolor separation element 137 and the light C1+C3 of the other wavelengthband to travel in the first diagonal direction. The eighth colorseparation element 138 may be configured to allow the light C2 of thesecond wavelength band to travel in a direction directly under theseventh color separation element 137 and the light C1+C3 of the otherwavelength band to travel in the second diagonal direction. In light ofthe above, the eighth color separation element 138 has the same colorseparation characteristics as those of the seventh color separationelement 137 and is rotated by 90° with respect to the seventh colorseparation element 137, or may correspond to the fourth color separationelement 134 that is oriented in the first diagonal direction. For theimage sensor of FIG. 15, as indicated by arrows, the first pixel 110 aand the third pixel 110 c may receive the light C1+C3 of the first andthird wavelength bands respectively from the first and second diagonaldirections.

It should be understood that the exemplary embodiments described hereinshould be considered in a descriptive sense only and not for purposes oflimitation. Descriptions of features or aspects within each exemplaryembodiment should typically be considered as available for other similarfeatures or aspects in other exemplary embodiments.

While one or more exemplary embodiments have been described withreference to the figures, it will be understood by those of ordinaryskill in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the exemplaryembodiments as defined by the following claims.

What is claimed is:
 1. An image sensor comprising: a pixel arrayincluding Bayer patterns, each of the Bayer patterns including a firstpixel and a third pixel provided in a first diagonal direction and twosecond pixels provided in a second diagonal direction crossing the firstdiagonal direction; and a color separation element provided to face thesecond pixels in the second diagonal direction, wherein the colorseparation element is configured to control light of a first wavelengthband of incident light to travel in a first lateral direction of thecolor separation element toward the first pixel, to control light of athird wavelength band of the incident light to travel in a secondlateral direction of the color separation element toward the thirdpixel, and to control light of a second wavelength band of the incidentlight to travel in a downward direction of the color separation elementtoward the second pixels, wherein the color separation element has ashape of a transparent rod and partially cover the second pixels.
 2. Theimage sensor of claim 1, further comprising a color filter layer that isprovided on the pixel array, wherein the color filter layer comprises atleast one of a first color filter provided adjacent to the first pixel,a second color filter provided adjacent to the second pixel, and a thirdcolor filter provided adjacent to the third pixel.
 3. The image sensorof claim 2, further comprising: a transparent dielectric layer providedon the color filter layer; and a microlens provided on the transparentdielectric layer.
 4. The image sensor of claim 3, wherein the microlensis provided to face the pixel array including the Bayer patterns.
 5. Animage sensor comprising: a pixel array including Bayer patterns, each ofthe Bayer patterns including a first pixel and a third pixel provided ina first diagonal direction and two second pixels provided in a seconddiagonal direction crossing the first diagonal direction; colorseparation elements provided to face the second pixels, respectively;and a color filter layer provided on the pixel array, wherein each ofthe color separation elements is configured to control light of a secondwavelength band of incident light to travel in a downward direction ofthe color separation element and to control mixed light including amixture of light of a first wavelength band of the incident light andlight of a third wavelength band of the incident light to travel indirections toward left and right sides of the color separation element,wherein the color separation element has a shape of a transparent rodand partially cover the second pixels.
 6. The image sensor of claim 5,wherein one of the color separation elements comprises a first colorseparation element provided in a first direction and a second colorseparation element provided in a second direction perpendicular to thefirst direction.
 7. The image sensor of claim 6, wherein the first colorseparation element and the second color element are alternately providedto face the second pixels.
 8. The image sensor of claim 6, wherein bothof the first color separation element and the second color element areprovided adjacent to one of the second pixels.
 9. The image sensor ofclaim 5, wherein the color separation elements are oriented in thesecond diagonal direction.
 10. The image sensor of claim 5, wherein oneof the color separation elements comprises a first color separationelement oriented in the first diagonal direction and a second colorseparation element oriented in the second diagonal direction.
 11. Theimage sensor of claim 5, further comprising: a transparent dielectriclayer provided on the color filter layer; and microlenses provided onthe transparent dielectric layer, wherein the microlenses are separatelyprovided at each of the first, second, and third pixels.
 12. The imagesensor of claim 11, wherein the light of the second wavelength bandseparated by the color separation elements is incident on the secondpixels and the mixed light of the first and second wavelength bands anda white light are incident together on the first and third pixels. 13.The image sensor of claim 12, wherein the color filter layer comprises afirst color filter provided on the first pixel and configured totransmit the light of the first wavelength band and a third color filterprovided on the third pixel and configured to transmit the light of thethird wavelength band.
 14. The image sensor of claim 12, wherein thelight of the first wavelength band is red light, the light of the secondwavelength band is green light, and the light of the third wavelengthband is blue light.
 15. An Image sensor comprising: a pixel arrayincluding a first pixel and a third pixel provided in a first diagonaldirection and two second pixels provided in a second diagonal directioncrossing the first diagonal direction; and a first color separationelement oriented in the second diagonal direction and facing the secondpixels, wherein the color separation element has a shape of atransparent rod and partially cover the second pixels.
 16. The imagesensor of claim 15, further comprising a second color separation elementoriented in the first diagonal direction and facing the second pixels.17. The image sensor of claim 16, wherein the first color separationelement is configured to control light of a first wavelength band ofincident light to travel in a first lateral direction of the first colorseparation element toward the first pixel, to control light of a thirdwavelength band of the incident light to travel in a second lateraldirection of the first color separation element toward the third pixel,and to control light of a second wavelength band of the incident lightto travel in a downward direction of the first color separation elementtoward the second pixels.
 18. The image sensor of claim 16, wherein thesecond color separation element is configured to control light of afirst wavelength band of incident light to travel in a first lateraldirection of the second color separation element toward the first pixel,to control light of a third wavelength band of the incident light totravel in a second lateral direction of the second color separationelement toward the third pixel, and to control light of a secondwavelength band of the incident light to travel in a downward directionof the second color separation element toward the second pixels.
 19. Theimage sensor of claim 15, further comprising a color filter layer thatis provided on the pixel array, wherein the color filter layer comprisesat least one of a first color filter provided adjacent to the firstpixel, a second color filter provided adjacent to the second pixel, anda third color filter provided adjacent to the third pixel.
 20. The imagesensor of claim 19, further comprising a transparent dielectric layerprovided on the color filter layer, wherein the first color separationelement is buried in the transparent dielectric layer.